In order to supplement the gas source and adjust the peak , Foshan natural gas pipeline network Company built the Ming City LNG station. The inherent characteristics and the potential risks of LNG demand a highly reliable monitoring and control system to guarantee the safety of LNG station.This paper analyses the SCADA development status of domestic and overseas LNG station, considered the special requirements of Ming City LNG station,Using monitoring software and PLC to integrate monitoring system . After analysing and discussing advantages and disadvantages of several monitoring software, choose the MOSAIC monitoring software of Australia LogicaCMG company. Siemens S7-400 PLC CPU and S7-300 PLC input/output module are the choice. S7 414-4H CPU can redundant.In accordance with the needs of process control, developed monitoring software based on the MOSAIC and application program of PLC, PLC complete complete data acquisition, logic, alarm output tasks, monitoring software is responsible for data display, important data storage, alarm manage, remote valve control and other functions. By comparing several communication programme, determine the means of communication, Fibre-optical communication is the primary means of communication between Ming City LNG station and company dispatch Center, GPRS wireless communication is secondary. According to trade measurement requirements, build a metering system base turbine flowmeter. Analysis of the measurement error during the testing process and provide solutions for reduce errors.Consider monitoring system test run results,analyses reliability,security and development of SCADA system.Ming City LNG station has put into operation for eight months, practice has proved that the SCADA system is high reliability and security, development and so on. Not only meet current LNG station monitoring requirements, but also leave the space can be extended in phase II project in the future. |